The disclosure herein relates generally to analyzer systems and methods, e.g., annular-acceptance analyzer systems. More particularly, the disclosure herein pertains to sample holder apparatus for such systems and methods (e.g., that may be mounted on an analyzer instrument stage).
It has long been recognized that the energy resolution of a cylindrical mirror analyzer (CMA), or other analyzers with annular acceptance (whether full 360-degree azimuthal acceptance or partial, that is, less than 360 degree azimuthal acceptance), is determined by the geometry of the analyzer. In such an instrument, (ΔE)/E is equal to a constant determined by the geometry of the instrument (where E is the kinetic energy of electrons passing through the analyzer in electron·volt (eV) and ΔE is the energy width (i.e., the analyzer “slit width”) or the range of electron energies passed by the analyzer around and at E). Furthermore, it has been recognized that if the energy of electrons entering an annular-acceptance analyzer (such as a CMA) is reduced, the effective resolution of the instrument is increased.
U.S. Pat. No. 3,699,331, entitled “Double Pass Coaxial Cylinder Analyzer with Retarding Spherical Grids,” discloses a device and method for reducing the energy of electrons entering a CMA using a retarding grid assembly constructed of two concentric spherical sections. One disadvantage of this approach is the loss in transmission due to two effects. First, the physical transparency (typically 60-90% each) of the grids limits the number of electrons transmitted. Second, when an electric field terminates on a grid of finite mesh, the equipotential surfaces are rippled close to the grid. Each grid opening acts as a lens which causes the transmitted electrons to be scattered from their original trajectory. The effect of grid scattering is to reduce transmission. A second disadvantage of this approach is the aberrations introduced by the non-sphericity of the fine grids (which are easily distorted during manufacture and assembly) and the non-concentricity of the two grid sections. A third disadvantage of this approach is the possibility of grid contamination and consequent need for grid replacement. A final disadvantage of this approach is the necessity of electrically floating the CMA, electron detector, and associated electronics.
Japan Pat. Appl. No. JP2006-302689A, entitled “Auger Electron Spectral Analysis Device and Auger Electron Spectral Analysis Method,” discloses a method that applies positive bias voltage to a sample electrode holder and alleges that, with this, kinetic energy of Auger electrons is reduced and high-resolution spectra are obtained.
There exists a need to reduce the energy of electrons entering a CMA without incurring the disadvantages caused by the use of grids for pre-retardation.